Digital cameras in the megapixel range are commonplace due to the fact that silicon, the semiconductor material of choice for large-scale electronics integration, readily converts photons at visual wavelengths into electrons. On the other hand, imaging outside the visible wavelength range is considerably more expensive. Hyperspectral and multispectral imaging have a wide range of applications. Current embodiments of hyperspectral imaging systems are bulky, expensive and relatively slow. Single pixel imaging systems can offer unique advantages, including significant cost savings, but maintaining a broad spectral response can create a somewhat more complex optical path requiring additional splitters, mirrors, and filters.
Present single-pixel camera architectures can compute pseudo-random linear measurements of a scene under view and reconstruct the image of the scene from the measurements. Scene under view can comprise light emanating from the object under view, where emanating can refer to radiating, transmitting, refracting, and/or reflecting from the object under view. The pseudo-random linear measurements are inner products between an N-pixel sampled version of the incident light field from the scene and a set of two-dimensional sampling functions. The inner product can be implemented via a digital micromirror device (DMD) consisting of a two-dimensional array of N mirrors that reflect the light towards only a single photodetector or away from it. The photodetector integrates the incoming light and converts it to an output voltage that is related to the magnitude of the inner product between the scene and the sampling function according to which the DMD is configured. Reconstruction of the image is possible by judicious processing of the set of estimated inner product values. One of the main limitations of the above described single-pixel camera architecture is that it is restricted to a single wavelength band.